Project Summary/Abstract Low exercise capacity is an important risk factor for all-cause morbidity and mortality. Skeletal muscle is a critical component of exercise capacity through its ability to generate ATP via mitochondrial substrate oxidation (i.e. mitochondrial function). Skeletal muscle properties also influence whole-body insulin sensitivity which affects risk for metabolic diseases (e.g. type 2 diabetes, obesity). Nascent myogenic progenitor cells are a critical component of skeletal muscle plasticity in response to exercise as they proliferate, self?renew and pass on epigenetic modifications to daughter populations. Meager evidence suggests that these progenitor cells are ?imprinted? by lifestyle interventions which confers subsequent metabolic adaptations. The proposed studies will fill a gap in our knowledge and directly assess the ability of exercise training to imprint myogenic progenitor cells in a manner leading to improved exercise capacity and reduced risk for metabolic disease. The primary goal of the present proposal is to leverage the MoTrPAC parent project and determine the distinct abilities of short-term (three months) and life-long (athletes) aerobic training (AT) and resistance training (RT) to imprint key myocellular metabolic properties (insulin sensitivity, mitochondrial function) through epigenetic regulation (DNA methylation, RNA expression) of novel exercise response genes in skeletal muscle progenitor cells. Our secondary goal is to establish a human primary skeletal muscle cell (HSkMC) culture repository from MoTrPAC which can be utilized for future mechanistic interrogations. We hypothesize that exercise training will imprint metabolic properties in skeletal muscle progenitor cells through epigenetic regulation of novel exercise response genes that will differ between AT and RT. We will establish HSkMC cultures from muscle biopsies of 325 individuals (AT, RT, control groups) before and following three months of intervention and 75 athletes (AT and RT) and assess insulin action (insulin-stimulated glycogen synthesis, insulin signal transduction), mitochondrial function (O2 consumption using carbohydrate and fatty acid substrates), DNA methylation and RNA expressions (RNAseq) with associated pathway enrichment analyses. The stated purpose of Aim 1 is to determine the distinct abilities of short-term and life-long AT and RT to imprint key myocellular metabolic properties (insulin sensitivity, mitochondrial function) through epigenetic regulation of exercise response genes. Integration of DNA methylation and RNAseq data will identify novel exercise response genes for subsequent genetic manipulation in vitro to determine its effects on the stated metabolic endpoints. The stated purpose of Aim 2 is to create an HSkMC repository for future investigations. Findings from the proposed studies will provide unprecedented mechanistic insight into the ability of exercise training to confer a ?metabolic memory? through epigenetic modification of specific exercise response genes and inform subsequent exercise prescriptions relative to optimizing health benefits gained from exercise.